(1) Field of the Invention
This invention relates to a method for controlling yellow nutsedge using the rust fungus.
(2) Description of the Prior Art
Yellow nutsedge, Cyperus esculentus L., is thought to be one of the world's most troublesome weeds. This weed has been a serious pest for many decades. In recent years it has spread rapidly throughout the United States and is now the most troublesome perennial weed in most of the Midwest.
Yellow nutsedge reproduces prolifically. One tuber plated in a field in Minnesota produced 1900 plants and 6900 tubers in 1 year. In Georgia 622 tubers were produced from one tuber in 17 weeks.
In spite of considerable effort, biocontrol methods for yellow nutsedge have not shown much success. Rust caused by Puccinia Canaliculata was first described in 1832. In 1906, it was demonstrated that Xanthium sp. was an alternate host, and indication that the pathogen is a macrocyclic heteroecious rust. Another possible alternate host is giant ragweed, Ambrosia trifida L. To our knowledge, no research has been reported on using this rust fungus to control yellow nutsedge. Researchers have observed the rust on yellow nutsedge in many locations in the United States and Canada. However, it usually does not appear until August and does not increase substantially until September. By then, the nutsedge has produced new seed and tubers and its life cycle is unaffected by the rust.